It is proposed to investigate the biosynthesis of the two microbial metabolites, compound 593A (NSC-135758) and elaiomycin. The major objectives of this work are: a), to establish the biogenetic origin of the carbon atoms in the skeletons of 593A and elaiomycin; b), to investigate the mechanism of chlorine introduction in 593A biosynthesis; c), to investigate the biogenetic origin of the azoxy function present in elaiomycin and; d), to examine the mechanism of formation of the piperidine ring in 593A if the antibiotic proves to be derived from homolysine. The methods which will be utilized include; a), the administration of specifically labeled precursors to Streptomyces griseoluteus and Streptomyces gelaticus followed by location of the labels in the antibiotics via degradation or c.m.r. spectrometry and, b), precursor incorporation experiments with "doubly labeled" precursors containing carbon-14 and nitrogen-15.